Add to pan. Pour the mixture into a lightly greased 13 x 9-inch metal baking pan. To grease your pan you can use shortening, butter, or even cooking spray.
Make pudding. While cake bakes make the pudding by adding 2 cups of milk to the vanilla pudding mix, whisking it together and then placing the pudding in the fridge to firm up.
Add pudding to the cake. Let the cake cool completely then use the end of a wooden spoon to poke holes across the entire top. Spread the vanilla pudding over the cake making sure it gets in all the holes.
Add banana slices. Cut 2 of the fresh bananas into slices. Place the fresh banana slices in rows on top of the pudding covering the top of the cake.
Add wafers and whipped cream. Sprinkle the crushed Nilla wafers over the bananas. Spread the whipped cream frosting over the cake making sure to completely cover the bananas and Nilla Wafers.
Add more banana and serve. Right before serving, cut the remaining banana into slices and top the cake with whole Nilla Wafers and banana slices. Serve immediately.